The present invention relates to photonic band-gap materials.
In many applications of lasers or other radiation sources, it is important to prevent reflected radiation from interacting with the source. Reflected radiation generates undesirable noise and unwanted feedback. Photonic or optical circuits is just one example of an application where there exists a need to isolate a source from reflected radiation.
As is known in the art, the Faraday effect in magneto-optical materials rotates the polarization of an incident beam as it passes through the material. Because of their Faraday effect, magneto-optical materials are used in non-reciprocal devices to serve as an isolator, i.e., a device that permits the transmission of light in only one direction. By placing an isolator near the radiation source in the path of propagating light, the isolator allows the emitted light to pass through. Any reflected light from the optical circuit is not permitted to pass through the isolator. Instead, the isolator blocks-out the reflected light, preventing the light from interacting with the source. However, traditional isolators are large, prohibiting them to be fabricated on an optical chip. A smaller isolator capable of being formed on an optical chip and produce a large Faraday rotation is thus desirable.